Based on a developed analytical model, a method is proposed for measuring the photonuclear cross section averaged over bremsstrahlung flux without application of additional target-monitor of photon ...flux. The method involves the use of a thin isotopic target, that completely overlaps the photon beam (a photonuclear converter), as well as an algorithm for processing the data on the yield of a reaction under study in such a target. The novel technique was validated on the reactions 100Mo(γ,n)99Mo and 58Ni(γ,n)57Ni in the range of photon end-point energy of 40.7–93.9 MeV. The photon flux-weighted average cross sections of the reactions measured experimentally are in good agreement with Monte Carlo simulations and TALYS predictions on their excitation functions.
•Effect of bremsstrahlung converter thickness on photon flux-weighted average (PFWA) cross section is shown.•Reference spectrum for above-threshold bremsstrahlung photons and its realization are proposed.•Weight function for bremsstrahlung photons integrable with reaction cross section in Lorentz form is derived.•Explicit relationship between Lorentz parameters of giant dipole resonance and PFWA cross section has been established.
An analytical method is used to describe isotope production at an electron accelerator. The key characteristics that determine the total target activity and its distribution have been established. ...The expressions for the reaction yield depend explicitly on the irradiation regime and parameters of the giant dipole resonance. The model predictions for the bremsstrahlung spectrum and yield of the reference reactions are in good agreement with the results of simulation and experiment.
•A simple formula for spectrum of high-energy X-rays is proposed and verified.•The formula enables convolution of X-ray spectrum with photonuclear cross-section.•Explicit expressions for photonuclear isotope yield have been obtained.•Good agreement is shown between the predicted and measured isotope yield.
When an electron accelerator operates in the bremsstrahlung generation regime, the initial beam is transformed in the extraction facilities of the accelerator into a flux of secondary particles – ...electrons and bremsstrahlung photons (
e,X
radiation). The ratio of the radiation components in a given plane depends on the initial energy of the electrons and the thickness and materials used for the extraction components. This article describes a simplified method for evaluating the main characteristics of
e,X
radiation in the radiation formation channel. The method is based on measuring the thickness of the components of the channel in units of electron path lengths in the continual stopping approximation. This makes it possible to express the radiation characteristics of materials with a wide range of atomic numbers (7–73) and electron energies (5–100 MeV) in a unified form. The possibilities of the method are demonstrated by the results of a simulation using the PENELOPE/2006 system of computer programs.
We present various properties of the production of the X(3872) and ψ(2S) states based on 10.4 fb−1 collected by the D0 experiment in Tevatron pp collisions at √s = 1.96 TeV. For both states, we ...measure the nonprompt fraction fNP of the inclusive production rate due to decays of b-flavored hadrons. We find the fNP values systematically below those obtained at the LHC. The fNP fraction for ψ(2S) increases with transverse momentum, whereas for the X(3872) it is constant within large uncertainties, in agreement with the LHC results. The ratio of prompt to nonprompt ψ(2S) production, (1 − fNP)=fNP, decreases only slightly going from the Tevatron to the LHC, but for the X(3872), this ratio decreases by a factor of about 3. We test the soft-pion signature of the X(3872) modeled as a weakly bound charm-meson pair by studying the production of the X(3872) as a function of the kinetic energy of the X(3872) and the pion in the X(3872)π center-of-mass frame. For a subsample consistent with prompt production, the results are incompatible with a strong enhancement in the production of the X(3872) at the small kinetic energy of the X(3872) and the π in the X(3872)π center-of-mass frame expected for the X þ soft-pion production mechanism. For events consistent with being due to decays of b hadrons, there is no significant evidence for the soft-pion effect, but its presence at the level expected for the binding energy of 0.17 MeV and the momentum scale Λ ¼ M(π) is not ruled out.
The muon system of the Run II DØ detector Abazov, V.M.; Alkhazov, G.; Baldin, B. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
11/2005, Letnik:
552, Številka:
3
Journal Article
Recenzirano
Odprti dostop
We describe the design, construction, and performance of the upgraded DØ
muon system for Run II of the Fermilab Tevatron collider. Significant improvements have been made to the major subsystems of ...the DØ
muon detector: trigger scintillation counters, tracking detectors, and electronics. The Run II central muon detector has a new scintillation counter system inside the iron toroid and an improved scintillation counter system outside the iron toroid. In the forward region, new scintillation counter and tracking systems have been installed. Extensive shielding has been added in the forward region. A large fraction of the muon system electronics is also new.
NeuLAND (New Large-Area Neutron Detector) is the next-generation neutron detector for the R3B (Reactions with Relativistic Radioactive Beams) experiment at FAIR (Facility for Antiproton and Ion ...Research). NeuLAND detects neutrons with energies from 100 to 1000 MeV, featuring a high detection efficiency, a high spatial and time resolution, and a large multi-neutron reconstruction efficiency. This is achieved by a highly granular design of organic scintillators: 3000 individual submodules with a size of 5 × 5 × 250 cm3 are arranged in 30 double planes with 100 submodules each, providing an active area of 250 × 250 cm2 and a total depth of 3 m. The spatial resolution due to the granularity together with a time resolution of σt≤ 150 ps ensures high-resolution capabilities. In conjunction with calorimetric properties, a multi-neutron reconstruction efficiency of 50% to 70% for four-neutron events will be achieved, depending on both the emission scenario and the boundary conditions allowed for the reconstruction method. We present in this paper the final design of the detector as well as results from test measurements and simulations on which this design is based.
Numerous applications of Earth observation (EO) data for Earth resource exploration both for land use management purposes and for fundamental research goals require as much as possible independent EO ...data sets provided for a number of data consumers, i.e. for collective (shared) data usage. In addition data distribution procedures should be accompanied with sophisticated information services enabling correct interpretation and application of provided data. As a result data providers should be able to convert data in a lot of consumer-proper formats and in some cases it should require additional data processing before data shipping. Presented work proposes basic infrastructure for collective (shared) EO data usage that enables above mentioned integration of information resources contained in typical Russian EO centers. Paper reveals architecture design, description of basic infrastructure elements, and examples of real implementations.
We present a measurement of the forward-backward asymmetry in the production of B(±) mesons, A(FB)(B(±)), using B(±)→J/ψK(±) decays in 10.4 fb(-1) of pp̄ collisions at sqrts=1.96 TeV collected by ...the D0 experiment during Run II of the Tevatron collider. A nonzero asymmetry would indicate a preference for a particular flavor, i.e., b quark or ̄b antiquark, to be produced in the direction of the proton beam. We extract A(FB)(B(±)) from a maximum likelihood fit to the difference between the numbers of forward- and backward-produced B(±) mesons. We measure an asymmetry consistent with zero: A(FB)(B(±))=-0.24±0.41 (stat)±0.19 (syst)%.
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